This exact thing happened to me. Luckily I got him back a day later. He just managed to find a way to wiggle out of my fenced yard in the time it took me to grab a ball to throw him. It's been a year and a half now and he wouldn't do that again now that he knows where home is. (I also added rabbit fencing to better secure my fence line.)
You aren't a bad owner. Things like this happen sometimes. 1/3 dogs get lost at some point in their lives.

If you live them, let them go!
But no, really, you should go find your dog, keep a better eye on them and if you don't have a fence that will keep your dog in your yard, do not get a dog. Or, do not let them outside when you aren't going to pay attention to what they are doing.

This exact thing happened to me. Luckily I got him back a day later. He just managed to find a way to wiggle out of my fenced yard in the time it took me to grab a ball to throw him. It's been a year and a half now and he wouldn't do that again now that he knows where home is. (I also added rabbit fencing to better secure my fence line.)
You aren't a bad owner. Things like this happen sometimes. 1/3 dogs get lost at some point in their lives.

Ignore the people saying you don't deserve a dog. One of my dogs got out once because she saw the hole under the gate and wanted to know what was on the other side of it. Once she found out, she just sat there by the gate until we found her. The hole was filled up and covered immediately afterward.

Sometimes dogs do those things. It's not your fault; you just have to be really careful about leaving them chances to roam, and make sure you know what to do if they get out. Luckily, most well-trained dogs, once used to their home, won't go very far.